The pelvis is a ring-like structure made up of three bones, the sacrum and two innominate bones that have three parts, the ilium, ischium, and pubis. The ring-like structure of the pelvic bones gives them great strength. Since the structure is ring-like, however, a fracture in one part of the structure will often be accompanied by another fracture or severe ligamentous injury at other points in the pelvic ring. Surgery is often required to repair the damage. Screws, bolts and metal plates facilitate the healing of the bones, and external fixators are common.
However, when external fixators are used, they may need to remain in place for as long as six to twelve weeks. Meticulous observation is required to spot signs of infection at the pin sites and note pins that are loosening and need to be replaced. Therefore, internal anchors are generally preferred. However, placing a plate on the bone requires a significant operation with resulting high blood loss. In some cases, a straight intramedullary screw may be placed along a curved path. While the screw is less invasive, because of the ring-shaped structure and curvature of the pelvic bones, the fixation may be inadequate because the straight screw cannot be implanted very far into a curved bone. This may result in inadequate fixation. Moreover, the screw must be relatively small in diameter to avoid extending through the bone. Surgically speaking, implanting a screw such that it extends from the bone can result in significant hazard to the patient because it may puncture or otherwise impinge upon important vascular and nervous structures.
Curved anchors and apparatus for forming curved holes for receiving the anchors can therefore be advantageous. Modified Kirschner wires having an angled distal tip may be driven into cancellous bone by a hammering action to form curved holes. Surgical drills provide only rotative motion in one or both directions of rotation and do not have a hammering capability. Therefore, in addition to a surgical drill, a hammering device or mechanism will also be needed during a fixation to drive the wire into the bone.
In order to simplify the tools, and/or the number of tools required by a surgeon for fixing bone fractures where curved fixation paths are required, there remains a need for an attachment device for a bi-directional rotary drill, such as a surgical drill, to convert the rotary drill to a hammer drill for driving modified drill wires into bone to produce curved bores for accepting bone anchors for fixing curved bone portions.